Association between wearable device usage and obesity transition in children and adolescents: a nationwide longitudinal study

Aim: Wearable devices have the potential to promote healthy behaviors, yet evidence on their effectiveness in pediatric populations remains scarce. This study aims to investigate the association between wearable device usage and the transition to obesity among Chinese children and adolescents, addressing critical gaps in evidence regarding optimal usage patterns and subgroup variations for obesity prevention. Methods: Using longitudinal data from the 2019-2020 National Student Physical Health Survey (n = 5,006), this study examined associations between wearable device/mobile app usage frequency (categorized as frequent, sometimes, occasional, rare, or never use) and obesity transition among children and adolescents aged 9-18. Multivariable logistic regression models adjusted for demographics were employed, with subgroup analyses stratified by age, sex, and residence. Results: Compared to frequent users, rare/never users showed a tendency toward higher risks of transitioning to obesity [odds ratio (OR) = 1.50, 95% confidence interval (CI): 1.04-2.18, P = 0.030]. Sometimes users had the lowest risk of physical inactivity (OR = 0.61, 95%CI: 0.51-0.73, P < 0.001), whereas never users demonstrated a higher risk of prolonged sedentary behavior (OR = 1.36, 95%CI: 1.11-1.67, P = 0.003). Subgroup analyses revealed stronger associations in rural areas (OR = 2.99, 95%CI: 1.23-7.25, P = 0.016 for overweight transition in occasional users) and boys (OR = 1.96, 95%CI: 1.05-3.68, P = 0.035 for overweight transition in rarely users). Conclusion: Moderate, rather than frequent, use of wearable devices may optimally mitigate obesity risk in children, potentially avoiding technology fatigue from overuse. Rural-urban and gender disparities highlight the need for context-specific interventions. Wearable device use may mitigate pediatric obesity risk primarily by reducing sedentary behavior and increasing physical activity time, with optimal benefits at moderate usage frequency. These findings emphasize prioritizing usage quality over device adoption rates in public health strategies.